Reflective/transmissive type liquid crystal display pannel, 2d/3d switching liquid crystal display panel, and 2d/3d switching type liquid crystal display

ABSTRACT

A transflective type liquid crystal display panel used as a displaying liquid crystal panel in a 2D/3D switching type liquid crystal panel, wherein a color filter having a colored layer and a transparent layer is provided on an opposing substrate. The transparent layer is formed to face only the reflective region of an active matrix substrate (region where a reflective electrode is formed), and serves as a diffuser processed layer. Accordingly, a liquid crystal display panel having a 2D/3D switching function and a transflective function can prevent moire in 2D display and at the same time provide good 3D display.

TECHNICAL FIELD

The present invention relates to a transflective liquid crystal displaypanel used as a displaying liquid crystal panel in a 2D/3D switchingtype liquid crystal display panel capable of switching between 2Ddisplay and 3D display. The invention also relates to a 2D/3D switchingtype liquid crystal display panel incorporating the transflective liquidcrystal display panel, and to a 2D/3D switching type liquid crystaldisplay.

BACKGROUND ART

In a normal field of vision, the two eyes perceive views of the worldfrom two different perspectives due to their spatial separation withinthe head. The images from these two perspectives are then recognized asa stereoscopic image by the brain due to parallax of the two images. Byutilizing this principle, there has been developed a liquid crystaldisplay in which 3D (three-dimensional) display is carried out byparallax generated by causing an observer to see images from twodifferent points of view through the right eye and the left eye,respectively.

In some 3D liquid crystal displays, images from different points of vieware supplied to the respective eyes of the observer by first encodingthe left eye image and right eye image on the display screen accordingto e.g. color, polarization state, or display time, and then separatingthese images through a filter system of glasses worn by the observer. Inthis way, only images intended for the respective eyes are supplied tothe left eye and right eye of the observer.

In other liquid crystal displays, a display panel 101 is combined with aparallax barrier 101 having a light-transmitting region and alight-shielding region arranged in a stripe pattern. This allows anobserver to recognize a 3D image without using a visual assistance suchas the filtering system (autostereoscopic display). Specifically, aparallax barrier 102 gives specific viewing angles to the right eyeimage and left eye image generated by the display panel 101 (see FIG.8(a)). When viewed in a specific spatial viewing range, only imagesintended for the respective eyes are viewed by the observer, and a 3Dimage is recognized (see FIG. 8(b)).

Such a liquid crystal display device that carries out autostereoscopicdisplay by using the parallax barrier is disclosed in U.S. Pat. No.6,055,013 (Date of patent: Apr. 25, 2000) or Japanese Laid-Open PatentPublication No. 95167/1999 (Tokukaihei 11-95167, publication date: Apr.9, 1999), for example. In U.S. Pat. No. 6,055,013 (Date of patent: Apr.25, 2000), a patterned retardation plate is used as the parallaxbarrier.

Such a liquid crystal display employing a parallax barrier is alsodisclosed in U.S. Pat. No. 6,046,849 (Date of patent: Apr. 4, 2000), forexample. In the liquid crystal display disclosed in this publication, 3Ddisplay and 2D display (two-dimensional display) are electricallyswitched by providing a switching liquid crystal layer or the like as ameans of activating and inactivating the effect of the parallax barrier.That is, in accordance with ON/OFF of the switching liquid crystallayer, the display of U.S. Pat. No. 6,046,849 (Date of patent: Apr. 4,2000) performs 3D display when the effect of the parallax barrier isactivated, and performs 2D display when the effect of the parallaxbarrier is inactivated.

Meanwhile, in these years, a transflective liquid crystal display hasbeen developed, which allows both reflective display and transmissivedisplay on a single display screen. This type of transflective liquidcrystal display serves as a reflective display when used in brightsurroundings, so that desirable display can be carried out using ambientlight without consuming much power. In dark surroundings, the liquidcrystal display serves a transmissive display, so that desirable displaycan be carried out using the backlight.

Conventional transflective liquid crystal displays commonly adapt asystem as disclosed in U.S. Pat. No. 6,195,140 (Date of patent: Feb. 27,2001). The liquid crystal display (disclosed in U.S. Pat. No. 6,195,140(Date of patent: Feb. 27, 2001) has a structure in which, as shown inFIG. 9, pixel electrodes are disposed in a matrix through switchingelements (not shown) at respective intersections of gate bus lines 111and source bus lines 112 that are mutually orthogonal.

The pixel electrodes include a transparent electrode and reflectiveelectrode which are electrically connected to each other. Thetransparent electrode is formed on a transparent insulating layer (notshown) formed on the gate bus lines 111, the source bus lines 112, andswitching elements. The reflective electrode has an aperture for lighttransmission, and is formed on the transparent electrode. In the liquidcrystal display, reflective display is carried out in a region 113 wherethe reflective electrode is formed (that is, a reflective region: shadedregion in the figure), and transmissive display is carried out through atransmissive region (projected region in the figure) 114, i.e., theaperture formed through the reflective electrode.

In the liquid crystal display carrying out reflective display,microscopic irregularities are formed to prevent an image fromreflecting on the reflective electrode. The irregularities formed on thereflective electrode should be randomly disposed. However, forsimplicity of the process, the irregularities are formed by a recurrentpattern. When the recurrent pattern of the irregularities is periodic,the reflecting light at the reflective electrode generates a periodicinterference pattern, called moire, which deteriorates image quality.

In order to solve moire, in liquid crystal displays carrying outreflective display, normally, a diffuser process is carried out. In thediffuser process, fine particles are added to an adhesive layer which isused to attach a polarizer to the display surface side of a liquidcrystal display panel, so that moire can be prevented by the lightscattering effect of the fine particles.

However, in the conventional arrangement, the following problem occurswhen the 2D/3D switching display function and the transflective functionare used in combination in the same liquid crystal display panel.

As described with reference to FIG. 8 above, 3D display utilizeslinearity of light emitted from the backlight and transmitted throughthe liquid crystal display panel. Therefore, in 3D display, only thetransmissive region of each pixel is used, and the reflective region isnot used at all. Also, when 2D display is performed, since the diffusingprocess for preventing moire is performed over the entire liquid crystaldisplay panel, its effect also covers the transmissive region.

However, since the diffuser process gives the scattering effect to thelight that emerges from the display surface side of the liquid crystaldisplay panel, the display performance of 3D display utilizing linearityof light deteriorates significantly when the scattering effect is givento the outgoing light from the transmissive region of the liquid crystaldisplay panel.

In other words, when the 2D/3D switching function and the transflectivefunction are used in combination in the same liquid crystal displaypanel, desirable 3D display cannot be obtained while at the same timepreventing moire in 2D display.

DISCLOSURE OF INVENTION

The present invention was made to solve the foregoing problem. An objectof the present invention is to provide a liquid crystal display panelincluding a 2D/3D switching function and a transflective function, inwhich desirable 3D display can be obtained while at the same timepreventing moire in 2D display.

To attain the foregoing object, a transflective liquid crystal displaypanel of the present invention includes a reflective region forperforming reflective display; and a transmissive region for performingtransmissive display, the reflective region and the transmissive regionbeing provided for each pixel, and a diffuser process being performedonly in a portion corresponding to the reflective region.

The diffuser process utilizes the scattering effect of light to preventmoire, which is generated by microscopic irregular patterns formed on asurface of a reflective electrode. In other words, in a transmissiveregion where moire does not occur, there is no problem in performingdisplay even if the scattering effect due to the diffuser process cannotbe obtained.

On the other hand, when the transflective liquid crystal display panelis used as display image generating means in a 2D/3D switching typeliquid crystal display panel, the transmissive region is used forperforming both 2D display and 3D display. In 3D display, parallax isgiven to a right eye image and left eye image by utilizing linearity oflight. Thus, scattering the display light in the transmissive regionsignificantly deteriorates the performance of 3D display.

On the contrary, according to the foregoing arrangement, the diffuserprocess is carried out only in a portion corresponding to the reflectiveregion. As a result, the light scattering effect by the diffuser processdoes not occur in the transmissive region. Thus, the linearity ofdisplay light is not hindered and desirable 3D display performance isattained. As a result, desirable 3D display can be realized while at thesame time preventing moire in 2D display.

It is preferable that the transflective liquid crystal display panelfurther includes a color filter having a colored layer formed in aportion corresponding to both the transmissive region and the reflectiveregion; and a transparent layer formed only in a portion correspondingto the reflective region, wherein the diffuser process is performed onlyin the portion corresponding to the reflective region, by using at leastpart of the transparent layer as a diffuser processed layer.

In the transflective liquid crystal display panel, ambient light, whichis used as display light for the reflective region, is transmittedthrough the color filter or the liquid crystal layer twice. On the otherhand, incident light from a backlight, which is used as display lightfor the transmissive region, is transmitted through the color filter orthe liquid crystal layer only once. Therefore, if the color filter andthe liquid crystal layer have the same arrangement in the reflectiveregion and the transmissive region, the optical density of the colorfilter or the optical function of the liquid crystal layer becomedifferent between the reflective region and the transmissive region.

On the contrary, according to the foregoing arrangement, the colorfilter includes the colored layer and the transparent layer. With thetransparent layer formed in a portion corresponding to the reflectiveregion, the optical density of the color filter or the optical functionof the liquid crystal layer will not be too different between thereflective region and the transmissive region.

Furthermore, by using the transparent layer to also serve as a diffuserprocessed layer (a layer in which fine particles have been added toimpart light scattering effect to the base material such as a resin),the diffuser process can be performed only in a portion corresponding tothe reflective region, without requiring an additional diffuser process,that is, an additional step of forming the diffuser processed layer.

It is preferable in the transflective liquid crystal display panel thatthe color filter has an aperture through the colored layer in thereflective region, and a transparent layer is formed in the aperture.

According to this arrangement, the colored layer in the reflectiveregion has an aperture, and the transparent layer is formed in theaperture. Therefore, the light transmitted through the aperture is notabsorbed by the colored layer, and the optical density of the colorfilter in the reflective region can be reduced.

In other words, when the arrangement of the color filter is the same forthe reflective region and the transmissive region, the optical densityof the color filter is greater in the reflective region than in thetransmissive region because the light travels through this region of thecolor filter more often. However, as described above, by reducing theoptical density of the color filter in the reflective region, theoptical density of the color filter will not be too different betweenthe reflective region and the transmissive region.

It is preferable in the transflective liquid crystal display panel thata thickness of the colored layer in the color filter is thinner in thereflective region than in the transmissive region.

According to this arrangement, the thickness of the colored layer isthinner in the reflective region than in the transmissive region.Therefore, the absorptivity for each passage of light transmittingthrough the colored layer in the reflective region can be reduced. As aresult, the optical density of the color filter in the reflective regioncan be reduced. Thus, the optical density of the color filter will notbe too different between the reflective region and the transmissiveregion.

In the transflective liquid crystal display, it is preferable that athickness of the colored layer in the transmissive region is twice asthick as that in the reflective region.

According to this arrangement, substantially the same absorptivity canbe obtained for the light transmitting through the color filter in thereflective region twice and the light transmitting through the colorfilter in the transmissive region once. As a result, the same opticaldensity can be obtained in the transmissive region and the reflectiveregion.

It is preferable in the transflective liquid crystal display panel thatthe color filter has a step difference between a portion correspondingto the reflective region and a portion corresponding to the transmissiveregion, and the step difference causes a thickness of the liquid crystallayer in the reflective region to be thinner than that in thetransmissive region.

According to the arrangement, the formation of the transparent layercreates a surface step difference between a portion corresponding to thereflective region and a portion corresponding to the transmissiveregion. With the surface step difference, the thickness of the liquidcrystal layer in the reflective region is set to be smaller than that inthe transmissive region.

When the thicknesses of the liquid crystal layer is the same in thereflective region and the transmissive region, the light path of lightpassing through the liquid crystal layer is longer in the reflectiveregion than in the transmissive region, and the optical function of theliquid crystal layer is greater for this light. On the contrary, whenthe thickness of the liquid crystal layer is thinner in the reflectiveregion than in the transmissive region, the light path length andtherefore the optical function of the liquid crystal layer will not betoo different between the reflective region and the transmissive region.

Further, it is preferable that the transflective liquid crystal displayincludes transparent electrode formed in the portion corresponding tothe transmissive region; and a reflective electrode formed in theportion corresponding to the reflective region, wherein a stepdifference is created between the transparent electrode and thereflective electrode, and the step-difference sets a thickness ratio ofthe liquid crystal layer between the reflective region and thetransmissive region.

According to this arrangement, with the surface step difference in thecolor filter, and with the surface step difference between thetransmissive electrode and the reflective electrode, a thickness ratioof the liquid crystal layer can be suitably set between the reflectiveregion and the transmissive region.

It is preferable in the transflective liquid crystal display panel thata thickness of the liquid crystal layer in the transmissive region istwice as thick as that in the reflective region.

According to this arrangement, the light path length will not bedifferent between the reflective region and the transmissive region, sothat the same optical function can be obtained in the liquid crystallayer.

To attain the foregoing object, a 2D/3D switching type liquid crystaldisplay panel includes display image generating means, capable ofcarrying out 2D display and 3D display, for generating a display imageaccording to input image data; parallax barrier means for giving aspecific viewing angle to the display image in carrying out 3D display,so as to obtain a 3D effect; and switching means for activating andinactivating the effect of the parallax barrier means, so as to switch2D display and 3D display, the display image generating means being atransflective liquid crystal display panel.

To attain the foregoing object, a 2D/3D switching type liquid crystaldisplay of the present invention incorporates the 2D/3D switching typeliquid crystal display panel.

In accordance with the arrangement of the 2D/3D switching type liquidcrystal display panel and the 2D/3D switching type liquid crystaldisplay, desirable 3D display can be obtained while at the same timepreventing moire in 2D display, as in the transflective liquid crystaldisplay panel.

For a fuller understanding of the nature and advantages of theinvention, reference should be made to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view illustrating a schematic structure of atransflective liquid crystal display panel according to one embodimentof the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic structure of a2D/3D switching type liquid crystal display panel using thetransflective liquid crystal display panel as a displaying liquidcrystal panel.

FIG. 3(a) is a cross-sectional view of the patterned retardation plateused in the 2D/3D switching type liquid crystal display panel.

FIG. 3(b) is a plan view of the patterned retardation plate used in the2D/3D switching type liquid crystal display panel.

FIG. 4 is a diagram illustrating an optical axis direction in eachmember of the 2D/3D switching type liquid crystal display panel.

FIG. 5 is a cross-sectional view illustrating a modification example ofthe reflective tranmissive liquid crystal display panel of the presentinvention.

FIG. 6 is a cross-sectional view illustrating another modificationexample of the reflective tranmissive liquid crystal display panel ofthe present invention.

FIG. 7 is a cross-sectional view illustrating still another modificationexample of the reflective tranmissive liquid crystal display panel ofthe present invention.

FIG. 8(a) is a diagram illustrating an effect of giving a viewing angleby a parallax barrier.

FIG. 8(b) is a diagram illustrating viewing regions for a 3D displayscreen.

FIG. 9 is a plan view illustrating one example of a structure of anactive matrix substrate used in the transflective liquid crystal displaypanel.

BEST MODE FOR CARRYING OUT THE INVENTION

The following will describe the present invention in more detail by wayof examples and comparative examples. It should be noted, however, thatthe invention is not limited in any way by the following.

With reference to FIGS. 1 through 7, one embodiment of the presentinvention is described below.

First, FIG. 2 illustrates a schematic arrangement of a 2D/3D switchingtype liquid crystal display panel of the present embodiment. As shown inFIG. 2, for the 2D/3D switching function, the 2D/3D switching typeliquid crystal display includes a displaying liquid crystal panel 10, apatterned retardation plate 20, and a switching liquid crystal panel 30,which are bonded together.

The displaying liquid crystal panel 10 is provided as a TFT liquidcrystal display panel, and includes stacked layers of a first polarizer11, an opposing substrate 12, a liquid crystal layer 13, an activematrix substrate 14, and a second polarizer 15. Through wiring 51 suchas flexible printed circuits (FPC), the active matrix substrate 14receives image data corresponding to an image to be displayed.

That is, the displaying liquid crystal panel 10 is provided as displayimage generating means for generating a display image corresponding toimage data. Details of the displaying liquid crystal panel 10, which isalso provided as a transflective liquid crystal display panel, aredescribed later. As long as the displaying liquid crystal panel 10 has afunction of generating a display image, a display method (TN method orSTN method) and a driving method (active matrix driving or passivematrix driving) for the displaying liquid crystal panel 10 are notparticularly limited.

The patterned retardation plate 20 functions as a part of a parallaxbarrier. As shown in FIG. 3(a), the patterned retardation plate 20 hasstacked layers of a transparent substrate 21, an alignment film 22, anda liquid crystal layer 23 formed in this order. In an active area of thepatterned retardation plate 20, as shown in FIG. 3(b), a first region20A (shaded region in the figure) and a second region 20B (projectedregion in the figure) having different polarization states are arrangedalternately in stripes.

The switching liquid crystal panel 30 has stacked layers of adriver-side substrate 31, a liquid crystal layer 32, an opposingsubstrate 33, and a third polarizer 34. The driver-side substrate 31 isconnected to wiring 52. Through the wiring 52, a driving voltage isapplied to the driver-side substrate 31 when the liquid crystal layer 32is ON.

The switching liquid crystal panel 30 is provided as switching means forswitching a polarization state of light (light transmitted through theswitching liquid crystal panel 30) in accordance with ON/OFF of theliquid crystal layer 32. Specifically, the switching liquid crystalpanel 30 optically modulates the light (light transmitted through theswitching liquid crystal panel 30) differently in performing 2D displayand 3D display. Unlike the displaying liquid crystal panel 10, theswitching liquid crystal panel 30 does not need to be driven by matrixdriving. Driving electrodes for the driver-side substrate 31 and theopposing substrate 33 are formed over an entire surface of an activearea of the switching liquid crystal panel 30.

As to the 2D/3D switching function, described next is a displayoperation of the 2D/3D switching type liquid crystal display panelarranged in the foregoing manner.

To begin with, FIG. 4 illustrates an optical axis direction of eachmember of the 2D/3D switching type liquid crystal display panel shown inFIG. 2. In the liquid crystal panels and retardation plates, the opticalaxes shown in FIG. 4 are directed in the direction of a slow phase axisof the alignment film (i.e. a rubbing direction of the alignment film).In the polarizers, the optical axes are directed in the direction of atransmission axis.

In the arrangement of FIG. 4, incident light from a light source isfirstly polarized by the third polarizer 34 of the switching liquidcrystal panel 30. When 3D display is performed, the switching liquidcrystal display panel 30 is OFF, and functions as a half wave plate.

The light transmitted through the switching liquid crystal panel 30 isthen incident on the patterned retardation plate 20. In the first region20A and the second region 20B of the patterned retardation plate 20,rubbing directions (i.e. directions of slow axes) are different.Therefore, light transmitted through the first region 20A and lighttransmitted through the second region 20B are polarized differently. InFIG. 4, the polarization axis of the light transmitted through the firstregion 20A and the polarization axis of the light transmitted throughthe second region 20B are different by 90°. With the birefringenceanisotropy and thickness of the liquid crystal layer 23, the patternedretardation plate 20 is set to serve as a half wave plate.

The light transmitted through the patterned retardation plate 20 isincident on the second polarizer 15 of the displaying liquid crystalpanel 10. When 3D display is performed, the polarization axis of thelight transmitted through the first region 20A of the patternedretardation plate 20 is parallel to the transmission axis of the secondpolarizer 15. Therefore, the light transmitted through the first region20A is transmitted through the polarizer 15. On the other hand, thepolarization axis of the light transmitted through the second region 20Bforms an angle of 90° with the transmission axis of the second polarizer15. Therefore, the light transmitted through the second region 20B isnot transmitted through the polarizer 15.

According to the arrangement in FIG. 4, the function of parallax barrier(parallax barrier means) is attained by optical interaction between thepatterned retardation plate 20 and the second polarizer 15. According tothis arrangement, the first region 20A of the patterned retardationplate 20 serves as a transmissive region, and the second region 20B ofthe patterned retardation plate 20 serves as a cutoff region.

The light transmitted through the second polarizer 15 is subjected tooptical modulation in the liquid crystal layer 13 of the displayingliquid crystal panel 10. Here, the optical modulation is different forthe pixels undergoing black display and the pixels undergoing whitedisplay. Only the optically modulated light of the pixels undergoingwhite display is transmitted through the first polarizer 11, therebydisplaying an image.

Here, for 3D display, the light transmitted through the transmissiveregion of the parallax barrier and modified to have a specific viewingangle is transmitted through the displaying liquid crystal panel 10 insuch a manner that the light passes through pixels corresponding to animage for the right eye and pixels corresponding to an image for theleft eye. As a result, the right eye image and left eye image areseparated to have different viewing angles, and 3D display is carriedout.

In order to perform 2D display, the switching liquid crystal panel 30 isturned ON, so that the light transmitted through the switching liquidcrystal panel 30 will not be optically modulated. The light transmittedthrough the switching liquid crystal panel 30 is then transmittedthrough the patterned retardation plate 20 in such a manner that thelight transmitted through the first region 20A and the light transmittedthrough the second region 20B have different polarization states.

However, unlike 3D display, the switching liquid crystal display panel30 does not perform optical modulation in 2D display. Therefore, thepolarization axes of light beams transmitted through the patternedretardation plate 20 will be symmetrical with respect to thetransmission axis of the second polarizer 15. As a result, the lighttransmitted through the first region 20A of the patterned retardationplate 20 and the light transmitted through the second region 20B of thepatterned retardation plate 20 are transmitted through the secondpolarizer 15 at the same transmittance. Thus, the function of parallaxbarrier due to optical interaction between the patterned retardationplate 20 and the second polarizer 15 is not attained (that is, nospecific viewing angle is given), with the result that 2D display iscarried out.

Next, a specific structure of the 2D/3D switching type liquid crystaldisplay panel 10 is described with reference to FIG. 1. As noted above,the displaying liquid crystal panel 10 is a transflective liquid crystaldisplay panel used as a displaying liquid crystal panel in the 2D/3Dswitching type liquid crystal display panel which enables switchingbetween 2D display and 3D display. Note that, FIG. 1 shows a crosssectional structure for one pixel.

The displaying liquid crystal panel 10, as shown in FIG. 1, includes apair of opposing substrates (the front and the back) (that is, theopposing substrate 12 and the active matrix substrate 14 shown in FIG.2), and the liquid crystal layer 13, provided as an electro-optic layer,which is interposed between the opposing substrate 12 and the activematrix substrate 14. In FIG. 1, the first polarizer 11 and the secondpolarizer 15 illustrated in FIG. 2 are omitted. In the displaying liquidcrystal panel 10, one or more retardation plates may be inserted betweenthe polarizer 15 and the active matrix substrate 14 and between thefirst polarizer 11 and the opposing substrate 12, so as to provideoptical compensation together with the refractive index anisotropy ofthe liquid crystal layer 13. Inserting a retardation plate only betweenthe first polarizer 11 and the opposing plate 12 can also provideoptical compensation.

First, a specific structure of the active matrix substrate 14 isdescribed. The active matrix substrate 14 includes a transparentsubstrate 141, a transparent insulating layer 142, a transparentelectrode 143, a reflective electrode 144, and an alignment film 145,which are stacked in this order from the light incident side of thedisplaying liquid crystal panel 10 (light source side).

Scanning bus lines, data bus lines, and switching elements for drivingthe transmissive electrode 143 and the reflective electrode 144 areactually formed beneath the transparent insulating layer 142, thoughthey are omitted in FIG. 1. The transmissive electrode 143 and thereflective electrode 144 are electrically connected to drains of theswitching elements through contact holes provided through thetransparent insulating layer 142. With the switching elements providedbeneath the reflective electrode, an aperture ratio can be improved.

According to the example of FIG. 1, pixel electrodes provided on theactive matrix substrate 14 side are realized by the transmissiveelectrode 143 made of Indium Tin Oxide (ITO) etc., and the reflectiveelectrode 144 formed of a metal film. The transmissive electrode 143 isformed over all the pixels, while the reflective electrode 144 is formedin a portion of the pixel region over the transparent electrode 143.

Thus, each pixel is divided into a region where the reflective electrode144 is formed, and a region where the reflective electrode 144 is notformed. The region where the reflective electrode 144 is formed servesas a reflective region, while the region where the reflective electrode144 is not formed serves as a transmissive region. Also, the reflectiveelectrode 144 needs to have microscopic irregularities on its surface inorder to prevent an image from reflecting. To this end, in thetransparent insulating layer 142, a region corresponding to the regionwhere the reflective electrode 144 is formed has irregularities on itssurface, and the reflective electrode 144 is formed above the irregularsurface of the transparent insulating layer 142. The alignment film 145is deposited on the pixel electrodes realized by the transmissiveelectrode 143 and the reflective electrode 144.

In this manner, in the displaying liquid crystal panel 10 of the presentembodiment, the pixel electrodes formed on the active matrix substrate14 has a hybrid structure including the transmissive electrode 143 andthe reflective electrode 144. In the example of FIG. 1, the reflectiveelectrode 144 is formed above the irregular surface of the transparentinsulating layer 142, and on the transmissive electrode 143(electrically connected). However, it is not necessarily required toprovide the transmissive electrode 143 beneath the reflective electrode144. For example, The transmissive electrode 143 and the reflectiveelectrode 144 may be electrically connected to each other in portionswhere the edges (boarders) of the respective electrodes overlap.

Described next is a specific structure of the opposing substrate 12. Theopposing substrate 12 includes a transparent substrate 121, a colorfilter 122, an opposing electrode 123, and an alignment film 124, whichare stacked in this order from the light outgoing side (display side) ofthe displaying liquid crystal panel 10.

In the displaying liquid crystal panel 10, pixels are formed in aportion where the opposing electrode 123 of the opposing substrate 12and the pixel electrode of the active matrix substrate 14 face eachother. A color filter 122 is formed on the opposing substrate 12 inconformity with the pixels.

In the structure of FIG. 1, the color filter 122 has a stacked structureof a colored layer 122 a and a transparent layer 122 b. The coloredlayer 122 a has an aperture in a part of the reflective region, and thetransparent layer 122 b is formed over the aperture. Also, thetransparent layer 122 b is formed to face only the reflective electrode144 of the active matrix substrate 14 (in other words, the transparentlayer 122 b is formed only in the reflective region), so that a stepdifference is formed between the transmissive region and the reflectiveregion.

The alignment film 145 of the active matrix substrate 14 and thealignment film 124 of the opposing substrate 12 horizontally align theliquid crystal layer 13, which is interposed in between, for example.Also, for the liquid crystal layer 13, liquid crystal of an ElectricallyControlled Birefringence (ECB) mode is used in which incident light istransmitted and blocked by employing the birefringence of the liquidcrystal.

In the displaying liquid crystal panel 10, the diffuser process isperformed only on the transparent layer 122 b of the color filter 122.That is, the resin (for example, acrylic resin) making up thetransparent layer 122 b is mixed with fine particles (silica, or acrylicresin of, for example, a spherical shape having a different reflectiviveindex from the acrylic resin of the transparent layer 122 b), so as toscatter the light transmitting through the transparent layer 122 b. Inaddition, since the transparent layer 122 b is formed facing only thereflective electrode 144, the effect of the diffuser process works onlyon the reflective region.

The diffuser process takes advantage of the light scattering effect toprevent moire due to the reflecting light generated by the microscopicirregularities formed on the surface of the reflective electrode 144. Inother words, in the transmissive region where moire does not occur,display can be carried out without causing any problem even when thescattering effect due to the diffuser processes is not be obtained.

In the case where the transflective displaying liquid crystal panel 10described above is used for the 2D/3D switching type liquid crystaldisplay panel, the transmissive region is used for performing both 2Ddisplay and 3D display. In 3D display, linearity of light is utilized,and therefore display performance severely deteriorates when the displaylight is scattered. In the displaying liquid crystal panel 10, however,the scattering effect due to the diffuser process does not occur in thetransmissive region. Therefore, linearity of display light is ensured,and desirable 3D display performance can be realized.

As described above, in the displaying liquid crystal panel 10 of thepresent embodiment, the layer subjected to the diffuser process(hereafter referred to as “diffuser processed layer”) is in the colorfilter. However, the present invention is not limited to this. That is,in the 2D/3D switching type liquid crystal panel of the presentinvention, the diffuser process is required to exhibit its effect onlyin the reflective region of the transflective liquid crystal displaypanel used as the displaying liquid crystal panel. For example, adiffuser processed layer corresponding to only the reflective region maybe formed as a separate filter from the color filter.

However, forming the diffuser processed layer in the color filter isadvantageous because it does not require an additional step of formingthe diffuser processed layer, and enables the color filter to be formedwith the colored layer and the transparent layer. For these advantages,forming the diffuser processed layer in the color filter is highlypreferable. Details of the advantages of forming the diffuser processedlayer in the color filter are described below.

In the color filter 122 shown in FIG. 1, the colored layer 122 a (e.g.acrylic pigment-dispersed photosensitive resin) has the aperture in thereflective region, and the transparent layer 122 b is formed above theaperture. Optimizing the area and geometry of the aperture allows anoptical density of the colored layer 122 b to be controlled between thetransmissive region and the reflective region.

In other words, in the transflective liquid crystal display panel, adesired color is reproduced as follows. In the transmissive region, thisis achieved when the incident light from the backlight is transmittedthrough the color filter once. On the contrary, in the reflectiveregion, a desired color is reproduced when ambient incident light on thedisplay surface is transmitted through the color filter twice (back andforth).

Assume that a colored layer of a uniform thickness is provided in thetransmissive region and the reflective region without forming anaperture. In this case, the ambient light (used as display light) istransmitted through the color filter twice in the reflective region.Therefore, the absorptivity of the color filter becomes greater for thereflective region than for the transmissive region, with the result thatcolor reproducibility deteriorates.

On the other hand, when the color filter shown in FIG. 1 is used, theprovision of the aperture in the colored layer 122 a in the reflectiveregion prevents excess absorption of ambient light even when the ambientlight is transmitted through the color filter 122 twice. As a result,high reflectivity can be maintained, and the brightness of display canbe maintained at a practical level.

In this manner, in the color filter 122, providing the aperture in thecolored layer 122 allows reflectivity, color purity, and brightness inthe reflective mode to be freely adjusted without degrading color purityin the transmissive mode. In addition, an optimum optical density can beset for each of the transmissive region and the reflective region. Togive a specific example, when the area of the aperture of the coloredlayer 122 a in the reflective region is about one-eighth of the area ofthe reflective region, substantially the same absorptivity can beobtained for the light transmitted through the color filter 122 in thereflective region twice and the light transmitted through the colorfilter 122 in the transmissive region once (the same optical density canbe obtained for the transmissive region and the reflective region).

Note that, in the structure of FIG. 1, only a single transparent layer,the transparent layer 122 b, is provided corresponding to the reflectiveregion. However, the transparent layer may have a bilayer structure asshown in FIG. 5. The exemplary structure shown in FIG. 5 is the same asthat illustrated in FIG. 1 except that a color filter 125 is usedinstead of the color filter 122.

In the color filter 125 illustrated in FIG. 5, the colored layer 125 ahas the same structure as the colored layer 122 a in the color filter122 shown in FIG. 1. However, the transparent layer corresponding to thereflective region has a bilayer structure including transparent layers125 b and 125 c. The transparent layer 125 b corresponds to an apertureof the colored layer 125 a, and forms a flat surface with the coloredlayer 125 a. Also, the transparent layer 125 c is disposed on surfacesof the colored layer 125 a and the transparent layer 125 b,corresponding to the entire area of the reflective region. In thestructure of FIG. 5, only the transparent layer 125 c can be used as adiffuser processed layer. In this case, the effect of the diffuserprocess can be exhibited evenly over the entire reflective region.

In the color filter, in order to adjust the optical density in thereflective region, the colored layer may be designed to have differentthicknesses in the reflective region and the transmissive region asshown in FIG. 6, instead of forming the aperture in the colored layer asdescribed above. Specifically, in a color filter 126 of the opposingsubstrate 12 shown in FIG. 6, a transparent layer 126 b is formedcorresponding to the reflective region, so that the thickness of acolored layer 126 a formed on the transparent layer 126 b becomesthinner in the reflective region. The exemplary structure illustrated inFIG. 6 is the same as the structure illustrated in FIG. 1 except thatthe color filter 126 is used instead of the color filter 122. In thestructure of FIG. 6, the transparent layer 126 b also serves a diffuserprocessed layer.

In this example, when the thickness of the colored layer 126 a in thereflective region is about half of the thickness of the colored layer126 a in the transmissive region, substantially the same absorptivitycan be obtained for the light transmitted through the color filter 126in the reflective region twice and the light transmitted through thecolor filter 126 in the transmissive region once (the same opticaldensity can be obtained in the transmissive region and the reflectiveregion).

In all of the color filters 122, 125, and 126, the colored layer and thetransparent layer are formed such that a step difference is createdbetween the reflective region and the transmissive region. With the stepdifference, the optical function (change in retardation) of the lighttransmitted through the liquid crystal layer 13 will not be toodifferent between the reflective region and the transmissive region.

That is, in the transflective liquid crystal display panel describedabove, a desirable optical function for the transmissive region isachieved by the incident light from the backlight transmitted throughthe liquid crystal layer 13 once. On the other hand, a desirable opticalfunction for the reflective region is achieved by incident ambient lighton the display surface transmitted through the liquid crystal layer 13twice.

Assume the situation where the thickness of the liquid crystal layer isthe same in the transmissive region and the reflective region. In thiscase, the light path in the reflective region is twice as long as thatin the transmissive region. Accordingly, the optical function will bedifferent in the transmissive region and the reflective region, and as aresult display quality deteriorates.

On the other hand, in the color filter described above, the formation ofthe transparent layer creates a step difference between the reflectiveregion and the transmissive region. With the step difference, thethickness of the liquid crystal layer 13 becomes thinner in thereflective region than in the transmissive region. That is, thedifference in length of the light path is reduced between the reflectiveregion and the transmissive region, thereby reducing the difference inoptical function between the reflective region and the transmissiveregion.

Further, when the thickness of the liquid crystal layer 13 in thetransmissive region is set to be twice as thick as that in thereflective region, substantially the same optical function can beobtained in the reflective region and the transmissive region. This isdescribed below with reference to the structure shown in FIG. 1 as anexample. Specifically, by setting the surface step difference CFd of thecolor filter 122 to satisfy the following equation, the thickness of theliquid crystal layer 13 in the transmissive region can be made almosttwice as thick as that in the reflective region.Td=Rd+CFd(=Rd)=2Rd,where Td is the thickness of the liquid crystal layer 13 in thetransmissive region, Rd is the thickness of the liquid crystal layer 13in the reflective region, and CFd is the surface step difference of thecolor filter 122.

When adjusting the surface step difference CFd of the color filter aloneis insufficient to set a proper thickness ratio of the liquid crystallayer 13 between the transmissive region and the reflective region, astep difference may be created between the reflective region and thetransmissive region on the active matrix substrate 14 side.

FIG. 7 shows a structure in which a step difference is created betweenthe reflective region and the transmissive region on the active matrixsubstrate 14 side. In this case, the transparent insulating layer 146formed on the transparent substrate 141 corresponds to only thereflective region. A transmissive electrode 147 is formed on the bottomof the step difference created by the transparent insulating layer 146,while a reflective electrode 148 is formed on the top of the stepdifference created by the transparent insulating layer 146. Thetransmissive electrode 147 and the reflective electrode 148 areelectrically connected to each other by overlapping part of therespective edges.

In the structure shown in FIG. 7, the transparent insulating layer 146creates a step difference (Kd) between the transmissive electrode 147and the reflective electrode 148. By setting the surface stepdifferences CFd and Kd to satisfy the following equation, the thicknessof the liquid crystal layer 13 in the transmissive region can be madealmost twice as thick as that in the reflective region.Td=Rd+CFd+Kd,where Td is the thickness of the liquid crystal layer 13 in thetransmissive region, Rd is the thickness of the liquid crystal layer 13in the reflective region, and CFd is the surface step difference of thecolor filter 122.

Note that, in the structure shown in FIG. 7, the color filter 126illustrated in FIG. 6 is used for the opposing substrate 12. However,the color filter 122 shown in FIG. 1 or the color filter 125 shown inFIG. 5 may be used as well.

As described above, in the transflective liquid crystal display of thepresent embodiment, the diffuser process is performed only in a portioncorresponding to the reflective region. Therefore, the light scatteringeffect due to the diffuser process does not occur in the transmissiveregion. As a result, linearity of display light is not hindered anddesirable 3D display performance can be realized. Further, desirable 3Ddisplay can be obtained while at the same time preventing moire in 2Ddisplay.

Further, in the liquid display panel, a polarizer constitutes theoutermost layer closest to the display surface. In order to prevent theambient light from reflecting on the polarizer, an anti-glare (AG) oranti-reflection (AR) treatment is performed on the surface of thepolarizer.

However, the AG treatment utilizes the light scattering effect toprevent reflection, and, to this end, microscopic irregularities areformed on the surface of the polarizer. Therefore, like the diffuserprocessing, when the AG treatment has the adverse effect on theperformance of 3D display. Thus, in the 3D liquid crystal panel, the ARprocess is preferably used to prevent the ambient light from reflectingon the surface of the polarizer.

A transflective liquid crystal display panel of the present invention isused as the displaying liquid crystal panel 10 shown in FIG. 2, andcombined with the patterned retardation plate 20 and the switchingliquid crystal panel 30. In this way, a 2D/3D switching type liquidcrystal display panel of the present invention is realized. In addition,by incorporating driving circuits, a backlight, or other components, the2D/3D switching type liquid crystal display panel can realize a 2D/3Dswitching type liquid crystal display.

The invention being thus described, it will be obvious that the same waymay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

INDUSTRIAL APPLICABILITY

According to a configuration of the present invention, linearity ofdisplay light is not hindered and desirable 3D display performance canbe achieved. In addition, prevention of moire in 2D display anddesirable 3D display can be realized at the same time. Therefore, thepresent invention can be suitably applied to a transflective liquidcrystal display panel used as a displaying liquid crystal display panelin a 2D/3D switching type liquid crystal display panel capable ofswitching 2D display and 3D display. The invention is also suitable fora 2D/3D switching type liquid crystal display panel incorporating thetransflective liquid crystal display panel, and a 2D/3D switching typeliquid crystal display.

1. A transflective liquid crystal display panel, comprising: areflective region for performing reflective display; and a transmissiveregion for performing transmissive display, the reflective region andthe transmissive region being provided for each pixel, and a diffuserprocess being performed only in a portion corresponding to thereflective region.
 2. The transflective liquid crystal display panel ofclaim 1, further comprising a color filter having: a colored layerformed in a portion corresponding to both the transmissive region andthe reflective region; and a transparent layer formed only in a portioncorresponding to the reflective region, wherein the diffuser process isperformed only in the portion corresponding to the reflective region, byusing at least part of the transparent layer as a diffuser processedlayer.
 3. The transflective liquid crystal display panel of claim 2,wherein the color filter in the reflective region has an aperturethrough the colored layer, and a transparent layer is formed in theaperture.
 4. The transflective liquid crystal display panel of claim 2,wherein a thickness of the colored layer in the color filter is thinnerin the reflective region than in the transmissive region.
 5. Thetransflective liquid crystal display panel of claim 4, wherein athickness of the colored layer in the transmissive region is twice asthick as that in the reflective region.
 6. The transflective liquidcrystal display panel of claim 2, wherein the color filter has a stepdifference between a portion corresponding to the reflective region anda portion corresponding to the transmissive region, and the stepdifference causes a thickness of the liquid crystal layer in thereflective region to be thinner than that in the transmissive region. 7.The transflective liquid crystal display of claim 6, further comprising:a transparent electrode formed in the portion corresponding to thetransmissive region; and a reflective electrode formed in the portioncorresponding to the reflective region, wherein a step difference iscreated between the transparent electrode and the reflective electrode,and the step-difference sets a thickness ratio of the liquid crystallayer between the reflective region and the transmissive region.
 8. Thetransflective liquid crystal display panel of claim 6, wherein athickness of the liquid crystal layer in the transmissive region istwice as thick as that in the reflective region.
 9. A 2D/3D switchingtype liquid crystal display panel, comprising: display image generatingmeans, capable of carrying out 2D display and 3D display, for generatinga display image according to input image data; parallax barrier meansfor giving a specific viewing angle to the display image in carrying out3D display, so as to obtain a 3D effect; and switching means foractivating and inactivating the effect of the parallax barrier means, soas to switch 2D display and 3D display, said display image generatingmeans being a transflective liquid crystal display panel including: areflective region for performing reflective display; and a transmissiveregion for performing transmissive display, the reflective region andthe transmissive region being provided for each pixel, and a diffuserprocess being performed only in a portion corresponding to thereflective region.
 10. A 2D/3D switching type liquid crystal display,comprising a 2D/3D switching type liquid crystal display panelincluding: display image generating means, capable of carrying out 2Ddisplay and 3D display, for generating a display image according toinput image data; parallax barrier means for giving a specific viewingangle to the display image in carrying out 3D display, so as to obtain a3D effect; and switching means for activating and inactivating theeffect of the parallax barrier means, so as to switch 2D display and 3Ddisplay, said display image generating means being a transflectiveliquid crystal display panel including: a reflective region forperforming reflective display; and a transmissive region for performingtransmissive display, the reflective region and the transmissive regionbeing provided for each pixel, and a diffuser process being performedonly in a portion corresponding to the reflective region.